Merge branch 'lc-docs-guidelines-hyphens-titles' into 'master'

Add guideline for hyphens in titles

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/126982



Merged-by: Suzanne Selhorn <sselhorn@gitlab.com>
Co-authored-by: Lorena Ciutacu <lciutacu@gitlab.com>